Timing issue?

I replaced the head on my 93 B2600i earlier this year due to over heating, failed head gasket and major oil consumption (blue smoke screen up on start up).

However since then I have noticed a couple things have changed:
1) Less mileage. 2mpg average (8%) drop, was previously 27+ now I get 25 max
2) There seems to be a lack of power in the lower rpm range--from idle to about 3k
3) at about 3k I have a sudden surge in power and feel of efficiency from the motor--a very noticeable power band surge, like a 2 stroke motorcycle almost.

Could this be related to timing? I scribed the distributor to the mounting plate etc when I replaced the head, but have not checked it with a timing light, and seem to think that it looked slightly different assembled from when disassembled.

What should a timing light show at idle?
How about under load (revving up motor)?

Do our distributors use vac advance?

Checked the timing today--found the two bolts holding the distributor were not tightened down. Timing was at 4* ATDC (after top dead center), when it should have been at 5* BTDC (before top dead center). Fixed it, and viola! runs much better, no more bogging/lack of umph below 3k rpms. No more 2 cycle power band at 3k rpms. Hopefully mileage will go back up now, but will take another week to be sure!

That's not good, but good detective job there. Maybe use some blue Loctite, from our sister company.

Glad it's running better now, maybe you're not so "crazy"....